Electrosurgical devices utilize electrical current, such as radio frequency (RF) energy, to cut and to cauterize tissue. The electrical current is delivered via a tissue-contacting portion of the device. The current facilitates a clean tissue cut with little or no bleeding by rapidly heating the tissue without unnecessarily damaging adjacent tissue. Electrosurgical tools can also cauterize tissue separately from or together with a cutting procedure.
Instruments for performing electrosurgery generally include an energy source or generator, an active electrode for delivering electrical energy to tissue to be treated, a return electrode to complete the electrical circuit and conductors for coupling the energy source to the active and return electrodes. A monopolar electrosurgical instrument includes an active electrode for cutting tissue and a remotely located return electrode for providing a current return path. Typically, the return electrode is in contact with a relatively large tissue area, such as a portion of the lower torso, for dispersing exiting current to prevent burning of tissue.
Various types of open and closed surgical procedures utilize electrosurgical devices. Closed surgical procedures include arthroscopic, endoscopic, hysteroscopic, urologic, resectoscopic and laparoscopic procedures. For example, a hysteroscope is used in a closed surgical procedure for treatment of various conditions within a woman's uterine cavity. Typical uses of hysteroscopes include fibroid removal, intrauterine adhesion removal, endometrial ablation and correction of abnormal uterine bleeding.
Some surgical procedures, such as arthroscopic and hysteroscopic procedures, require distension of the surgical area in order to increase visibility at the treatment site or to minimize space constraints. In some instances the surgical area is distended using a fluid.
An electrolyte-free (i.e., hypotonic) distension fluid is typically used in such procedures to prevent the electrical current delivered by the active electrode from dissipating to an ineffective level. However, absorption of excess quantities of hypotonic solution into a patient's bloodstream can alter the patient's electrolyte levels and potentially result in dangerous conditions, including cardiac arrhythmia, brain swelling and even death. The risk of these dangers may cause the surgeon to terminate the procedure before completion. Furthermore, hypotonic solutions are expensive as compared to isotonic solutions.
Although monopolar electrosurgical instruments are useful, there is a need for instruments that are effective in isotonic solutions, especially those instruments useful in closed surgical procedures, such as arthroscopy, endoscopy, hysteroscopy, laparoscopy and resectoscopy.